From Atkins to Zone

Author: Winston Craig, MPH, PhD, RD.

How safe are popular weight loss diets?

“We are an overfed, over-advertised, and under-exercised nation”, says Dr Farquhar of Stanford University Center for Research in Disease Prevention. Partly to blame is the “enormous portion sizes and sitting in front of the TV and computer all day” he said recently. With Americans eating more and exercising less, obesity rates are climbing. So too is the interest in diet books.

With one out of two Americans overweight, the pursuit of weight loss has become a national way of life. All told, Americans spend $40 billion a year on weight loss regimens, and diet books have taken up permanent residence on the NY Times bestseller list.

Most of the popular diet books contain convincing testimonials and terrific promises, and explain why that diet works and all the others fail. Really though, which diet is the best? Which ones are safe? Do any of them work over the long haul? What do the human studies show? Can we make any sense out of the plethora of dietary advice in the current diet books?

The most popular diet books today promote the high protein/high fat diets such as the Atkins diet, Protein Power, Sugar Busters, and the Zone Diet all of which limit carbohydrates. The proponents of these low carbohydrate diets argue that a high carbohydrate intake produces high insulin levels and insulin, they say, is the monster hormone that causes obesity. They argue that limiting the carbohydrate intake forces the body to burn fat. Experts strongly disagree. They say no data exists to validate these claims.

Why do the high fat diets, such as the Atkins diet, work for some people? The monotony of a low carb diet with the ensuing ketosis can curb one’s appetite. When you eliminate pasta, rice, bread and other carbohydrate-rich foods from the diet there is less variety in the diet. The result is that people eat less, and so lose weight.

While high fat diets may promote short-term weight loss, the potential hazards for increasing the risk of atherosclerosis overrides any short-term benefits. The problem with the high fat diets are that they very high in saturated fat and cholesterol. Their long-term use would elevate blood lipids and increase the risk of coronary heart disease. In addition, these diets are also deficient in calcium, and low in dietary fiber.

Basically the popular diets that produce weight loss do so by cutting the calories. But the real issue is not simply whether they help with weight loss. The important issue it is how to achieve long-term weight management. Fad diets generally have a very low success rate in the long term. Within five years of losing weight on a fad diet, over 95 percent of those people regained the weight back again.

Dr. Rena Wing of Brown University Medical School has a National Weight Loss Registry that keeps track of people who report having lost at least 30 pounds and have kept the weight off for at least six years. The 3,000 people in the registry typically eat a low fat diet (an average of 24 percent of the calories as fat), and exercise the equivalent of a daily four mile walk.

Although the Fit for Life and the Ornish diets are low-fat diets, they are not recommended. The Fit for Life diet by the Diamonds is nutritionally unbalanced and it may lead to vitamin and mineral deficiencies. The diet is based upon an erroneous theory of detoxification. The Diamonds suggest that the build up of toxic wastes is the cause of obesity. The Ornish diet is a low-fat, high-fiber, high complex carbohydrate diet that sounds healthful. However, the fat content (10 percent of the calories) is considered too low for the average person. It would be appropriate to use as a therapeutic diet for persons with severe atherosclerosis. Ideally, the fat content of a diet should be at least 15 percent.

An increasing number of people are going online to get professional help for losing weight. Two of the sites having chat rooms with a dietitian and that provide an exercise plan include Cyber diet and eDiets. You can check them out at www.cyberdiet.com and www.ediets.com

The safest way to lose weight and enjoy long-term weight management is by making healthy lifestyle changes that last a lifetime. A modest consumption of a high complex carbohydrate diet containing high-fiber foods, and a modest fat intake, together with a regular exercise program is the best recommendation.